They shared one of the longest feuds in British politics, but Gordon Brown and Peter Mandelson began an extraordinary rapprochement earlier this year when the Prime Minister picked up the phone to Brussels and requested a meeting to clear the air.

Mr Mandelson, who became the European Commissioner for Trade in 2004 after his second exit from the Cabinet, has never been in exile in Brussels but always kept himself in the loop of top-level Labour politics through many close friendships, not least with David Miliband, the Foreign Secretary.

Mr Brown spent more than an hour in private talks with Mr Mandelson in Brussels in February focusing on the Doha Round of world trade talks which were then at a critical phase and have since failed, much to the disappointment of Mr Mandelson.

Despite forging ahead with bilateral trade agreements between the EU and various countries, he regarded the Doha disaster as the end of his main role in Brussels, leaving him with one more year to see out the term of his appointment which was due to next autumn.

The stand-off with Mr Brown, which had seen the former close friends barely talk socially since their dramatic falling out over Mr Mandelson’s backing for Tony Blair in the Labour leadership contest of 1994, was finally ended after almost 14 years.

In March 2007, the strength of the bad feeling between them was highlighted when Mr Mandelson told a BBC interviewer that Mr Brown would be unable to sack him as a commissioner. “I don’t know whether this is going to come as a disappointment to him, but he can't actually fire me. So like it or not, I'm afraid he will have to accept me as commissioner until November 2009. But I will not be seeking a nomination for a further term.”

The extent of the thaw after their meeting in February was shown when Mr Brown offered to nominate him as commissioner for a second term. This was leaked to the press and seemingly withdrawn by Mr Brown, a sign widely taken that the old feud was back on. But in reality Mr Brown has been picking up the phone regularly to Mr Mandelson for advice on global trade and business currents as well as, increasingly, how to stage a Labour fight-back in the polls.

Mr Mandelson will leave Brussels unfulfilled in two of his main aims: the collapsed WTO talks for which he travelled the world trying to keep alive; and his championing of Russia’s case to join the WTO, which has also fallen on stony ground in recent months after a promising start. He was also the subject of a poster by the No campaign in the Irish referendum on the Lisbon treaty, alleging that his free trade policies would ruin Irish farmers.

Mr Mandelson can never stay out of the headlines for long. After making up with Mr Brown he developed a new feud - with Nicolas Sarkozy, the French President, over the limits of the EU’s policy on free trade.

In June, Mr Sarkozy suggested that Mr Mandelson’s liberal negotiating stance over Doha would “cut farm output by 20 per cent while 800 million people are dying of hunger…Frankly, there is only one person who thinks like that and it is Peter Mandelson.”

Speaking to The Times, Mr Mandelson hit back: "To link this to hungry mouths in developing countries is disingenuous.

"Europe cannot possibly feed the rest of the world, but Europe can help the rest of the world to feed itself by reforming its trade-distorting agricultural policies, and that is simply what we are offering to do in the context of the Doha round."

Tellingly, Mr Brown was robust in leaping to Mr Mandelson’s defence in this row, saying: “We need this trade deal and he is pushing for it. We support him in the excellent work that he is doing.”

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